1. Field of the Invention
The present invention relates to endless tracks and more specifically to extended life track systems.
2. Description of the Related Art
The endless track has been incorporated in certain work machines for many years. Such an arrangement has shoes which engage the soil with a significantly larger foot print than wheels to enable significant traction and usefulness. Endless track assemblies are usually constructed with a series of pivotally interconnected links that form the structural foundation for shoes actually engaging the ground. The links also provide engagement with, among other things, a drive spoke that causes the assembly to move about its track. One of the key design features for such a system is the track pin which, while providing a pivotal interconnection for the links, also engages the teeth of the drive sprocket. Over the years, many efforts have been applied to a structure in which the track pins have extended life.
One such effort is to have rotating bushings that are positioned over the track pin and engage the teeth of the drive sprocket. The rotating track pin in extended life form involves a clearance between the track bushing and the track pin. This clearance is filled with appropriate lubricant to enable the rotation. Seals are provided at the axial ends of the track bushing to keep out dirt and other debris normally encountered in the operation of an endless track work machine. A problem with this arrangement is that dirt and other contaminants can migrate across the seal and destroy its effectiveness thereby allowing the lubricant to leak out and to eventually cause a termination of the service life. In addition to the cost of links, it is difficult to properly install such a track bushing so that it can be expected to have a reasonably extended service life.
Accordingly, what is needed in the art is a track bushing for an endless track assembly that avoids the issues associated with the prior art.